1. Field of the Invention
The present invention relates generally to a set-top-box based on an open cable.
More particularly, the present invention relates to an apparatus and a method for receiving broadcasts of an Out-Of-Band (OOB) channel and a Data Over Cable Service Interface Specification (DOCSIS) Set-top Gateway (DSG) channel using one tuner in a set-top-box.
2. Description of the Related Art
Digitalization of a broadcasting mediums including, for example, satellite broadcasting, sky waves, and cable broadcasting, are rapidly developing all over the world. This has caused a rapid growth in digital Set-Top-Boxes (STBs) that act as a medium for coupling the Internet with TeleVision (TV) and digital broadcasting.
A broadcasting program currently used for cable broadcasting uses various formats for encoding and modulation. Accordingly, manufacturers of STBs and broadcasting program providers have developed standards for broadcasting programs. For example, an open cable scheme has been proposed as a common standard for a digital broadcasting program. Channels for full duplex data communication that are supported by the open cable STB include, for example, a DSG channel and an OOB channel. Here, DSG channels are primarily used in Korea, and OOB channels are primarily used in the United States. Some service providers mount separate tuners in order to support both DSG channels and OOB channels.
FIG. 1 is a schematic block diagram illustrating the conventional STB. As illustrated in FIG. 1, the conventional STB includes a DSG tuner 100, an OOB tuner 102, a Quadrature Amplitude Modulation (QAM) demodulation Integrated Circuit (IC) 104, a Quadrature Phase Shift Keying (QPSK) demodulation IC 106, an output unit 108, a controller 110, and a memory 112.
A broadcast signal received via an antenna is divided and simultaneously input to the DSG tuner 100 and the OOB tuner 102.
The DSG tuner 100 selects a channel desired by a user according to a DSG scheme from broadcast signals received via the antenna under control of the controller 110. The QAM demodulation IC 104 demodulates a signal of the channel selected by the DSG tuner 100 to output an original data signal, and original video and/or audio signals. Additionally, the QAM demodulation IC 104 decodes signals separated by a data decoder, a video decoder, and an audio decoder, and transfers the decoded signals to the output unit 108 for display to the user.
Simultaneously, the OOB tuner 102 selects a channel desired by the user according to an OOB scheme from broadcast signals received via the antenna under control of the controller 110. The QPSK demodulation IC 106 demodulates a signal of the channel selected by the OOB tuner 102 to output an original data signal, and original video and/or audio signals. Additionally, the QPSK demodulation IC 106 decodes signals separated by a data decoder, a video decoder, and an audio decoder, and transfers the decoded signals to the output unit 108 for display to the user.
The DSG tuner 100 and the OOB tuner 102 perform tuning operations in accordance with the reception of a received DSG signal and a received OOB signal, respectively.
As described above, due to tuner characteristics, a single tuner may only tune a single broadcast frequency. A broadcast receiver is manufactured using two tuners by mounting both an OOB tuner for an OOB channel and a DSG tuner for a DSG channel according to a digital broadcast standard.
Since services are not provided simultaneously in the two channels, one of the OOB channel and the DSG channel is selected and used depending on a service provider. Therefore, it is a waste of resources to mount two tuners on one STB. In addition, since the STB is constructed with both the tuner for the DSG channel and the tuner for the OOB channel, a space inside the receiver is complicated and manufacturing costs and power consumption increase.